1. Technical Field
The present invention relates to a liquid ejecting apparatus such as an ink jet printer and a control method thereof, and more particularly, to a liquid ejecting apparatus in which a liquid is introduced from a liquid reservoiring member to a pressure generating chamber and is provided to a pressure generating element thereby to eject the liquid in the pressure generating chamber from a nozzle and a control method thereof.
2. Related Art
A liquid ejecting apparatus is an apparatus which includes a liquid ejecting head capable of ejecting a liquid and ejects a variety of liquids from the liquid ejecting head. The representative example of the liquid ejecting apparatus is an image recording apparatus, such as an ink jet printer (hereinafter, simply referred to as a printer) which includes an ink jet recording head (hereinafter, simply referred to as a recording head) and records an image or the like by ejecting and landing liquid ink onto a recording medium (landing target) such as a recording paper from nozzles of the recording head. In recent years, the liquid ejecting apparatus has been applied to a variety of manufacturing apparatuses such as an apparatus manufacturing a color filter for use in a liquid crystal display or the like, as well as the image recording apparatus.
The printer is configured so that pressure of the liquid in the pressure generating chamber is varied and ink is ejected from nozzles using the pressure variation. In such a printer, a pressure generating unit such as a piezoelectric vibrator is provided to correspond to each pressure generating chamber, and an ejection driving pulse is applied to the pressure generating unit so as to drive the pressure generating unit, thereby varying the pressure of the liquid in the pressure generating chamber. By controlling the pressure variation, the ink may be ejected. The ejection driving pulse is set to have various shapes in accordance with the type of the pressure generating unit for use or the amount of the ink to be ejected, etc. In this respect, it is important to minutely determine a driving voltage (which is a potential difference between the lowest potential and the highest potential) for any ejection driving pulse. This is because the amount of the ejected ink varies according to the size of the driving voltage. In addition, since the optimal value of the driving voltage is different for every recording head, the optimal value of the driving voltage is determined for every recording head (see JP-A-2003-011369).
However, for example, in the case that a so-called solid recording in which a predetermined region in the recording medium such as a recording paper is filled closely with dots without any gap is executed, the ink is continuously ejected from each nozzle with a short cycle by simultaneously driving a plurality of piezoelectric vibrators. In this case, a flow speed in an ink supply passage which extends from an ink cartridge to the recording head increases and flow resistance becomes high, thereby causing pressure loss. In other words, in the case that a large amount of ink is consumed as in the solid recording, a desired ejection characteristic is obtained immediately after starting an ejecting operation of the ink, whereas the weight or speed of the ink ejected from each nozzle is decreased as the flow speed of the ink in the ink supply passage increases. As a result, a problem such as variation in the density of an image to be recorded may occur.
In order to prevent such a problem, it is possible to adopt a method of dividing the image or the like which has been recorded with one main scanning (pass) of the recording head in the related art into a plurality of passes for recording. In this case, however, the recording speed decreases as the pass increases.